这个程序可以检查pop3邮件信息，纯粹的Winsock和Win32 API，不用 MFC以及Winsock2。所使用的API函数用到了CreateThread，GetOpenFileName，trayicons，SetTimer，sndPlaySound，GetExitCodeThread，TerminateThread等。消息通讯安全功能包括

1. 身份验证,使收件人确信发件人就是他或她就是公开密钥所对应的那个人

2. 机密性,确保只有预期的收件人能够阅读邮件

3. 完整性,确保消息在传输过程中没有被更改

4. 消息到达确认,发件人确认收件人收到了消息-This process can check pop3 e-mail messages, pure Winsock and Win32 API, not MFC and Winsock2. Used to use the API function CreateThread, GetOpenFileName, trayicons, SetTimer, sndPlaySound, GetExitCodeThread, TerminateThread and so on. Information communication security features include 1. Authentication, so that the recipient is convinced that the sender is that he or she is the public key corresponding to that person 2. Confidentiality, to ensure that only the desired recipient can read the e-mail 3. The integrity of to ensure that the information during transmission is not altered 4. to confirm the news arrived, the author confirmed that the recipient received the message